Resistance Test; Ground Test - Daikin APGM3 Service And Troubleshooting

SERVICING
Ignition of the discharge can also occur at the venting
terminal or inside the compressor, if there is sufficient
contaminant air present in the system and an electrical arc
occurs as the terminal vents.
Ignition cannot occur at the venting terminal without the
presence of contaminant air, and cannot occur externally
from the venting terminal without the presence of an
external ignition source.
Therefore, proper evacuation of a hermetic system is
essential at the time of manufacture and during servicing.
To reduce the possibility of external ignition, all open
flame, electrical power, and other heat sources should be
extinguished or turned off prior to servicing a system.

Resistance Test

Each compressor is equipped with an internal overload.
The line break internal overload senses both motor
amperage and winding temperature. High motor
temperature or amperage heats the disc causing it to open,
breaking the common circuit within the compressor on
single phase units.
Heat generated within the compressor shell, usually due to
recycling of the motor, high amperage or insufficient gas to
cool the motor, is slow to dissipate. Allow at least three to
four hours for it to cool and reset, then retest.
Fuse, circuit breaker, ground fault protective device, etc.
has not tripped -
High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be
present. Failure to do so may cause property
damage, personal injury or death.
1. Remove the leads from the compressor terminals.
See warnings before removing compressor terminal cover.
2. Using an ohmmeter, test continuity between terminals
S-R, C-R, and C-S.
WARNING
WARNING
Testing Compressor Windings
If either winding does not test continuous, replace the
compressor.
NOTE: If an open compressor is indicated, allow ample
time for the internal overload to reset before replacing
compressor.

Ground Test

If fuse, circuit breaker, ground fault protective device, etc.
has tripped, this is a strong indication that an electrical
problem exists and must be found and corrected. The
circuit protective device rating must be checked and its
maximum rating should coincide with that marked on the
equipment nameplate.
With the terminal protective cover in place, it is acceptable
to replace the fuse or reset the circuit breaker ONE TIME
ONLY to see if it was just a nuisance opening. If it opens
again, DO NOT continue to reset.
Disconnect all power to unit, making sure that all
power legs are open.
1. Carefully remove the compressor terminal protective
cover and inspect for loose leads or insulation breaks
in the lead wires.
2. Disconnect the three leads going to the compressor
terminals at the compressor or nearest point to the
compressor.
3. Check for a ground separately between each of the
three terminals and ground (such as an unpainted
tube on the compressor). If there is any reading of
continuity to ground on the meter, the compressor
should be considered defective.
4. If ground is indicated, replace the compressor.
Damage can occur to the glass embedded terminals if the
leads are not properly removed. This can result in terminal
and hot oil discharging.
WARNING
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